WiFi Sync for second password safe

Hey Guys,

I'm using the latest iOS Version of 1Password and 1Password 4.6.2.626 for Windows. I just made the in app purchase to be able to sync a second password safe with my App. Unfortunately when I want to add a second sync, it only offers the option to sync via dropbox.
Is this an intended behaviour or am I doing something wrong?

I need to be able to sync one safe with my PC and another safe with another my PC, using a cloud service which server is not in my control is not an option.

Thank you in advance,
Markus

1Password Version: 6.9
Extension Version: Not Provided
_OS Version: iOS 10.3.3
_Sync Type: WiFi